Answer
$f(x)= 1.2\cdot\left(2 \right)^x$
Work Step by Step
Let $f(x)=a b^x$. We know from the graph that $f(0)=a b^0= a=1.2$ and $f(2)= 1.2b^{2}=4.8$. So
$$
\begin{aligned}
(1.2) b^2 & = 4.8\\
b & =\left(4\right)^{\frac{1}{2}} \\
b=2 & \text { or } b=-2
\end{aligned}
$$
Hence
$f(x)= 1.2\cdot\left(2 \right)^x$
